Stabilizers for nitro-cellulose mixtures



United States Patent Ofi 2,696,430 Patented Dec. 7, 1954 ice STABILIZERSFOR NITRO-CELLULOSE MIXTURES John A. Gallaghan, Indian Head, Md., andIrving Pincus, State College, Pa., assignors to the United States ofAmerica as represented by the Secretary of the Navy No Drawing.Application May 3, 1950, Serial No. 159,872

7 Claims. (Cl. 525) (Granted under Title 35 U. S. Code (1952), see. 266)4-nitroaniline, incorporating them into powders, to lower the meltingpoint, and to improve the plasticizing qualities of these compounds.

Other objects of the invention will appear in and be apparent from thespecification.

In the preparation of experimental powders for possible stabilizers,several tests are useful to eliminate all but the most promising foraddition to the nitrocellulose. The results of these tests for certainof the compounds screened are tabulated for comparison. Samples used inthe 134.5 C. heat test are formed by mechanically extruding 12.6 percentpyrocotton with one-half /2) percent stabilizer, using ether and alcoholas a solvent. The product is allowed to stand one day in air and is thenplaced in a vacuum oven for eight (8) hours at 40 C. A standard 134.5heat test and a 5 hour test are run on the sample. The nitrogen dioxideabsorption and viscosity tests are conventional laboratory proceduresfor these purposes.

Screening tests for stabilizers N 02 Absorption at 25 0., Pressure inHeat Test Mercury Viscosity at 134.5 5 hour Change 1 Methyl Test, 10 110 (poises) Violet hrs. 1mm] seconds min. min. Final (mm') Diphenylamine72 32 22 20 1. 5 Ethyl-Oentralite 72 63 48 37 34 g0 82 6 7 86 N-Methyl-4-nitro anilme 72 0 0 0 58 103 5 60 105 N-ethyl-4-n1tro aniline72 7 1 0 5 1 Viscosity change at 0. for five days using an ethylCellosolve solution of cellulose nitrate The present method ofstabilizing single base powders is by adding diphenylamine, and indouble base powders by adding centralite. A disadvantage of usingdiphenylamine as a stabilizer is that it reacts with oxygen of the airand also with oxides of nitrogen to form black or dark colored dyes ofunproved structures. It further reacts with nitrogen dioxide and nitricacid to form nitrogen monoxide gas. Centralite also reacts with nitrogentetroxide to form nitrogen monoxide. Since it is the function of astabilizer to remove these undesirable products, these materials are notas eflective in removing oxides of nitrogen as the chemicals hereindisclosed.

The N-alkyl-nitroanilines which contain an alkyl group such as methyl,ethyl, isopropyl, etc., and contain a nitro group in the three or fourpositions on the benzene ring, when mixed in a nitro-cellulose powder,either single or double base, lead to a powder possessing superiorstability. N-methyl-4-nitroaniline, N-ethyl-4-nitroaniline, N-is1opropyl-3-nitroaniline, N-butyl-3-nitroaniline are examp es.

An important object of the present invention is the substitution of fromone-half to one percent (up to five percent) of N-ethyl-4-nitroanilineor N-methyl-4-nitroaniline or mixtures thereof in place of diphenylaminein single base nitro-cellulose powders and in place of ethyl centralitein double base nitrocellulose powders.

A further object of the invention is to produce a superior powder ofimproved stability which does not become discolored by oxidationimpurities.

A still further object of the invention is to make the aniline nitrogensufficiently neutral by the nitro group in N-alkyl-4-nitroanilines, sothat it would be compatible with nitroesters and still be a strongabsorbent of highly oxidized nitrogen atoms, such as nitric acid andnitrogen tetroxide.

Still a further object of the invention is to prepare a eutectic mixtureof N-ethyl-4-nitroaniline and N-methyl- The control dropped an averageof 30 poises for this period.

The results of the screening tests indicate that the N- alkylmononitroanilines possess excellent stabilizing prop erties for singlebase powder. They efiiciently absorb nitrogen dioxide reducing little ornone of it. They further do not aifect the viscosity of cellulosenitrate solution as much as diphenylamine. In the heat test which showsthe time in minutes to decolorize methyl violet paper, they comparefavorably with diphenylamine.

Double base powders were prepared by dissolving 60 percent cellulosenitrate (13.47% N), 39 percent nitroglycerine and 1 percent stabilizerin acetone and evaporating oif the acetone at room temperature. Theproducts were extended through a micro-press and placed in a vacuum ovenfor 7 days at 45 C. The comparative results are shown as follows:

H120 t 610 C.

- eat es aeuum Stabfluer (Average) Stability Minutes Test EthylCentralite (Control).. 65 8. 32

N-Methyl-4-nitroanlline- 90 8. 37

N -Ethyl-4-nitroaniline 8. 45

third more effective than ethyl-centralite in the heat test and-areaboutthe sameintheNaQuum-tests, "andtheresiqub q ba e; pow ers is. thus Preen ed .apnar nt y has improved and superior chara lemfliw, roduc ngia eer es lt than the ngredients-n w. cqrnmen y kno and used as stabilizers.

h invention described here nnay he manuia tq a d s b or o the GQ ernmwwt e -niteds ate Amerce f r gove nmenta pun s; wi hout he: Paym t of ny wa s the eon arft erefq st b iz e mn isin an I l a ky troan line .Q n rehan' pe ent b b l in com nati n withon qf the g o 9 96 919. ni re e'a dqellules nitrat tm ce in 1 h co hinat enz fi trocellul s .n wde am a kl- -nirroaml ae con itut a t b i er the or- 3. The combination of anitrocellulose powder and a s a ilize ther i 9 materiah leqt d t am erup consisting of N-ethyl-4-nitroan i1ine and H l\I -methyL-4nitroaniline of not more than 5 percent by bulk.

4. The combination of cellulose nitrate nitroglycerine powder and notmore than five percent by. bulkpf N1 methyl-4-nitroaniline constitutinga stabilizer'therefor;

5. A stabilizer for nitrocellulose powders comprising a mixtureof"N'-ethyl-4-nitroaniline and N-methyl-4-nitroanilineof-not more than 5percentfiby bulhiucorporate'd into a nitrocellulose powder with improvedplasticizing qualities.

References Cited in the file or this patent .SIATESPATEN S Number. NameI Date 875.922 mes. a 7. 9 8 875,923 Holmes Jan. 7, 1908 1,329,212Spelling et a1. Ian. 27, 1920 2,261,630 Regestein Nov. 4, 1941 2,323,948Von-'Bramenet a1 July 13, 1943 2,378,594 Swan et a1. June 19, 19452,381,015 Von Bramenet a1 Aug. 7,1945 2,383,361 Basset a1. Aug..'21,1945 F R N PATEN S.

Number Country Date 12,746 Great Britain of 1912 'DavisJohn' Wiley andSons, 1943, N. Y., vol. II, pp. 269

and 307-312.

1. A STABILIZER COMPRISING AN N-ALKYL-NITROANILINE OF NOT MORE THAN 5PERCENT BY BULK IN COMBINATION WITH ONE OF THE GROUP OF CELLULOSENITRATE AND CELLULOSE NITRATE NITROGLYCERINE.